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As this was a warm and sunny day with temperatures reaching a high of 28C, the report notes "it is possible" it may have heated the capacitor further.

It states: "This is because the traction equipment case is a dark colour (and would therefore easily absorb heat)."

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RAIB recommended to UK train operating companies and suppliers of their rolling stock to make sure adequate safeguards are in place to prevent a similar situation.

Along with this, they added a number of learning points ranging from project risk management, investigating technical failures and ensuring accurate and complete records of serious failures are maintained.

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